As is known, in regeneratively-heated coke ovens, a flue gas collector main extends along a battery of coke ovens and is connected to the regenerators of the coke ovens by changeover valves. The bottom outlet pipes of the changeover valves extend into apertures in the crown of the flue gas collector and, hence, serve as inlets for the flue gases which pass along the collector to a discharge point.
In the past, it has been customary to construct these flue gas collector mains from refractory bricks which form a base, side walls and an arched crown. The refractory bricks are often encased within a concrete outer wall with or without the addition of an insulating layer. The concrete casing is sometimes also required to bear supports or other parts of the coke ovens, including those serving to brace and anchor the oven masonry.
The production of a brick arch of the type described above necessitates a considerable outlay in terms of labor and material. The component parts which have to be made in brick masonary on the one hand and in concrete on the other hand are dependent upon one another as regards their fabrication and this may give rise to considerable delays if there are any difficulties in the delivery of some of the materials. In addition, the concrete casing or shell is subjected to thermal stresses; and after a long period of operation, this results in cracks and leaks and, in particular, necessitates a high degree of reinforcement in order to insure the load-bearing capacity of the concrete material.